The Greek verb anakainizo means "to renew" or "to restore to a fresh condition." It appears in Hebrews 6:6 in the solemn warning about those who fall away — it is impossible to renew them again to repentance.
The single occurrence of anakainizo in Hebrews 6:6 teaches that genuine renewal is a work of God's sovereign grace, not human manipulation. Repentance itself is a gift from God (Acts 11:18; 2 Timothy 2:25). This solemn warning is about deliberate, final apostasy — a warning that strengthens the call to persevere in faith.